The physicochemical properties of geraniin, a potential antihyperglycemic agent

Context: Natural products play a vital role in the discovery of leads for novel pharmacologically active drugs. Geraniin (GE) was identified as the major compound in the rind of Nephelium lappaceum L. (Sapindaceae), while ellagic and gallic acids have been shown to be its main metabolites. GE and its metabolites possess a range of bioactive properties including being an anti-infective, anticarcinogenic, antihyperglycemic, and antihypertensive. Objective: GE and its metabolites were investigated to establish its gastrointestinal absorption and physicochemical properties. Materials and methods: GE was purified from N. lappaceum rind extract using reverse-phase C18 column chromatography. Lipophilicity (log P) was determined using the 1-octanol/water shake-flask method. Equilibrium solubility of GE and its metabolites (20 mg) was determined in water and four biorelevant media: simulated gastric, simulated intestinal, fasted state-simulated intestinal, and fed state-simulated intestinal after 72 h. Results and discussion: The purification yield was 10.8%; where a 97-99% pure GE was obtained. Log P values for GE, ellagic, and gallic acids were established as -0.73+/-0.17, 0.11+/-0.06, and 0.71+/-0.21, respectively, establishing them as polar compounds. All three compounds were found to exhibit poor solubility in gastric (0.61-8.10 mg/mL) but good solubility in intestinal fluids (3.59-14.32 mg/mL). Conclusion: The above results indicate that the compounds have limited gastrointestinal absorption due to its polarities. To consider these compounds as oral drug candidates, formulation strategies are being developed.